Ankylosing spondylitis and bone mineral density—what is the ideal tool for measurement?

Abstract

Ankylosing spondylitis (AS) is characterised by chronic inflammation and partial ossification, yet vertebral fractures due to osteoporosis, although common, are frequently unrecognised. The aim of this study was to (1) show the frequency of changes in the progress of osteopenia/osteoporosis in AS depending on duration and stage of the disease and (2) assess the ranking of two different methods of bone density measurement in this clinical pattern. We measured bone density in 84 male and female patients with both dual X-ray absorptiometry (DXA) and single energy quantitative computed tomography (SE-QCT). In the initial and advanced stages of the disease, a high decrease in axial bone density could be verified (DXA: osteopenia in 5% and osteoporosis in 9.2%; SE-QCT: osteopenia in 11.8% and osteoporosis in 30.3%). Peripheral bone density decrease as in osteopenia could be proven in 17.6% by DXA measurement. With SE-QCT, a decrease in vertebral trabecular bone density could already be observed in the initial stage and continued steadily during the course of the disease; cortical bone displayed the same trend up to stages of ankylosis. With DXA, valid conclusions are more likely to be expected in less marked ankylosing stages of AS. In stages of advanced ankyloses in the vertebral region (substantial syndesmophytes), priority should be given to SE-QCT, due to the selective measurement of trabecular and cortical bone. The DXA method often yields values that are too high, and the replacement of vertebral trabecular bone by fatty bone marrow is not usually recorded as standard. There may already be an increased risk of bone fracture in AS in osteopenia on DXA along with an osteoporosis already established on SE-QCT.

Osteopenisi Olan Ankilozan Spondilitli Hastalarda Kemik Mineral Yoğunluğu ile Hastalık Aktivitesi Arasındaki İlişkinin Değerlendirilmesi

“…Çalışmamızda, osteopenisi olan AS'li hastalarda kemik mineral yoğunluğu ile hastalık aktivitesi arasında ilişki bulunmamıştır. AS'de kemik kaybı hem omurgada hem de femur boyun bölgesinde hastalığın erken döneminden başlayarak ileri dönemlerinde de devam eder (10). Özellikle ilaçlara rağmen inflamasyonun engellenemediği ve hastalık süresinin uzun olduğu durumlarda kemik kaybı fazladır (11,12).…”

Relationship Between Bone Mineral Density and Disease Activity in Patients with Ankylosing Spondylitis

“…Significant positive correlation between QCT results at the lumbar spine and DEXA results at the femoral neck had been reported in the same study (25). Lange et al (2) showed bone mass loss by QCT at the lumbar spine in both early and late AS patients. Nevertheless, lateral lumbar DEXA may be more suitable for serial BMD measurements because it has lower radiation dose than QCT.…”

“…Inflammatory enthesopathy progressing to ossification and ankylosis is the pathologic basis of the disease (1). A considerable decrease in bone mineral density at lumbar spine and femoral neck has been observed in AS (2). Osteoporotic vertebral fracture rates have ranged from 0% to 18% (3).…”

Lessons from Genomic Profiling in AS

“…Ossification is the hallmark of AS and has been linked to aberrant activation of bone morphogenic protein (BMP) and wingless (WNT) signaling. Bone resorption, driven by the impact of inflammation on the bone remodeling cycle, occurs simultaneously, with up to 56% of patients developing systemic osteopenia and some of them systemic osteoporosis (Lange et al, 2005).…”